The present invention relates to aircraft or flight vehicles which utilize essentially fixed shaped, non-rotating airfoil surfaces to generate primary lift and which show high stability in flight operations, particularly at low forward speeds such as for short field take-off and landing (STOL) or vertical take-off and landing (VTOL) operations.
There has been considerable interest in flight vehicles of this type and various types of aircraft said to have these characteristics have been proposed. For example, Shew, U.S. Pat. No. 2,957,647 discloses an aircraft of this type which utilizes a pair of upwardly and rearwardly opening channel members located forward of a conventional main wing structure; Hartman, U.S. Pat. No. 2,994,493 discloses a channel fan aircraft in which the powerplant causes air to flow through a ducting channel; Binder, U.S. Pat. No. 3,017,139 discloses a series of ring airfoil aircraft of this type; and Bertelsen, U.S. Pat. No. 3,572,614 discloses an aircraft generally of this type.
The current interest in VTOL and STOL flight vehicles of the type here involved is strongly motivated by advances in remotely piloted vehicle (RPV) technology and optical and electronic surveillance technologies which favor use of platforms of this type.